This relates generally to imaging systems, and more particularly, to imaging systems with stacked integrated circuit dies.
Modern electronic devices such as cellular telephones, cameras, and computers often use digital image sensors. Imaging systems (i.e., image sensors) often include a two-dimensional array of image sensing pixels. Each pixel typically includes a photosensitive element such as a photodiode that receives incident photons (light) and converts the photons into electrical signals. The imaging system contains an image sensor die with an image sensor integrated circuit and an array of photodiodes. The image sensor die is mounted on a digital signal processor (DSP) die.
In conventional imaging systems, a first wafer that includes multiple image sensor dies is mounted on top of a second wafer that includes multiple DSP dies. The first and second wafers may then be cut along scribe line regions to dice the stacked wafers into individually stacked dies. Typically, the scribe line regions are devoid of any silicon substrate material. The lack of silicon substrate material in the scribe line regions may present challenges when forming color filter array structures for the image sensor die since the upper surface of the image sensor die tends to be non-uniform when at least a portion of the silicon substrate is removed in the scribe line regions.
In such arrangements, at least some oxide material is disposed in the scribe line regions. The interface between the oxide material in the scribe line regions and adjacent silicon substrate material may be also be prone to damage and cracking during dicing operations.
It would therefore be desirable to provide imaging systems with improved scribe line regions.